The latest non prescription brow serums are supposed to enhance the thickness of the brow hairs you do have and help stimulate growth in areas that are sparse. You don't need to see a doctor to get a serum (as you do with the lash-and-brow enhancer Latisse). Apply once or twice a day (following package directions) and, the companies claim, you'll see results in as little as two weeks.

What the pros say

There are dozens of over-the-counter brow serums, but they're not all created equal, stresses Francesca Fusco, MD, a dermatologist in New York City. The best of these OTC formulas pack peptides, adds Joshua Zeichner, MD, director of cosmetic and clinical research in dermatology at Mount Sinai Hospital in New York City. (Some other serums rely only on essential oils, which simply strengthen the hair you already have.)

Petptides are "messengers designed to do a specific job—in this case, encourage hair growth and healthy hair follicle activity," explains Dr. Zeichner. Products with peptides include ($80; ), ($50; or ), and ($110; , , or ). (The makers of RevitaBrow stop short of promising actual hair growth, however.)

"RapidBrow has proved to be the go-to among my patients," says Dr. Fusco. Most people tolerate peptide serums well, the experts say, but they can cause irritation; discontinue use if you notice redness, itching, or swelling.

What we say

Although brow regrowth doesn't happen overnight, these peptide-rich picks add fullness. For those with sensitive skin, we like VegaBrow; in addition to peptides, it contains anti-inflammatory botanical ingredients, such as red clover and mung bean, which are gentle on your skin. However, if it's serious brow rehab you're after, you may want to go straight to RapidBrow. No matter which serum you try, if you use it regularly you should see a boost in the condition of your arches.